You can always file a motion seeking that, if there are proper grounds to do so. But, unless the judge made a finding of factual innocence at the time as the reason for the dismissal, you have no assurance he will do so now. Dismissals happen all the time when the DA decides not to prosecute. That doesn't mean 'factual innocence', only that the DA's case had some issue with evidence or procedure. If serious about hiring counsel to do this, feel free to contact me.